Method of manufacturing terminal-modified polymer

ABSTRACT

A terminal-modified polymer is manufactured by performing a polymerization reaction of a vinyl aromatic monomer, a conjugated diene monomer or both in the presence of an anionic polymerization initiator: and then adding an alkoxy aluminum compound thereinto to terminate the polymerization reaction. Alternatively, a terminal-modified polymer can also be manufactured by adding an aluminum halide compound instead of the alkoxy aluminum compound to terminate the polymerization reaction, and allowing for a reaction with a lower alcohol having 1 to 4 carbon atoms. The resulting terminal-modified polymer can improve the dispersibility of silica used as a compounding agent in rubber compositions for automobile pneumatic tires and the like.

TECHNICAL FIELD

The present invention relates to a method of manufacturing aterminal-modified polymer. More particularly, the present inventionrelates to a method of manufacturing a terminal-modified polymer whichimproves the dispersibility of silica used as a compounding agent in arubber composition for an automobile pneumatic tire and the like.

BACKGROUND ART

Various performances required for automobile pneumatic tires includereduced rolling resistance, stability on a wet road and the like. As amethod that can balance these properties, silica is compounded in arubber composition for tires as a reinforcing filler. However, thefollowing problem has been encountered: although silica is compounded ina rubber composition for tires, the dispersibility of silica into therubber composition is low. Therefore, even in a case where a largeamount of silica can be added, the effect of silica can not be fullyobtained.

Patent Document 1 describes a method of manufacturing anelastomer/filler composite useful as a tire component and the like, themethod comprising forming in situ a reinforcement filler from aprecursor thereof in an elastomer•host material to uniformly dispersethe reinforcement filler. In this case, in order to compound silica as afiller, a reaction from a filler precursor is required in PatentDocument 1.

Patent Document 2 describes a method of manufacturing anelastomer/filler composite material, comprising: blending a fillerprecursor, a condensation reaction accelerator and an elastomer host (A)or (B) in a closed mixer to initiate a condensation reaction of thefiller precursor; adding an organosilane material and a filler/fillerprecursor to the closed mixer before completion of the condensationreaction to allow for a reaction with regard to the elastomer host (A)and optionally the elastomer host (B); and collecting the resultingelastomer/filler composite material. Further the document states thatthis composite material may be used as an active ingredient of a rubbercomposition for tires, in particular a rubber composition for tiretreads.

This document describes that the elastomer host (A) is a homopolymer ofa conjugated diene or a copolymer of a conjugated diene and a vinylaromatic monomer while the elastomer host (B) is an elastomer based onat least one diene terminally functionalized with alkoxy metal, whereinthis diene based elastomer is represented by the following generalformula (claim 5, paragraph [0014]):

elastomer-X—(OR)n

wherein

-   -   elastomer: a homopolymer of a conjugated diene or a copolymer of        a conjugated diene and a vinyl aromatic monomer    -   X: a metal comprising Si, Ti, Al or B    -   R: a C₁-C₄ alkyl group    -   n: 3 for Si and Ti, and 2 for Al and B

However, Patent Document 2 only describes, in Examples, that styrene and1,3-butadiene is copolymerized in an organic solvent in the presence ofa lithium based catalyst, and then the resulting elastomer is collected.The document does not describe a method of manufacturing aterminal-modified polymer in which an -X—(OR)n group is introduced as anelastomer terminal group.

Further, Patent Document 3 describes a method of manufacturing aterminal acid anhydride group-containing polymer, comprising: allowingan ate complex comprising a living polymer and a typical metal elementsuch as aluminum to react with a diester compound such as di-tert-alkylmaleate to prepare a polymer having a terminal diester group; and thenthe diester group is converted into an acid anhydride group.

With regard to the ate complex used in the above method, in a case whereanionic polymerization of styrene is first performed using butyllithium, a polymer terminal will become —C⁻Li⁺ unless the reactionstops. Li⁺ in this —C⁻Li⁺ belongs to a hard acid as used in the field ofthe HSAB theory, and therefore the paired —C⁻ shows high reactivity. Ingeneral, the —C⁻ being highly reactive (nucleophilic) also attacks acarbonyl carbon under this condition. As a result of this, introductionof an acid anhydride group is difficult. Therefore, it is carried outthat a hard acid is often converted into a soft acid.

As a method of achieving this, an approach is used in the above patentdocument in which the reactivity is reduced by using a trialkyl aluminumcompound having no leaving group, i.e., by transforming —C⁻Li⁺ into—C⁻(AlR₃Li)⁺.

PRIOR ART DOCUMENTS Patent Literature

Patent Document 1: JP-A-2000-273191

Patent Document 2: JP-A-2000-143881

Patent Document 3: JP-A-2007-084711

OUTLINE OF THE INVENTION Problem to be Solved by the Invention

An object of the present invention is to provide a method ofmanufacturing a terminal-modified polymer which improves thedispersibility of silica used as a compounding agent in a rubbercomposition for an automobile pneumatic tire and the like.

Means for Solving the Problem

An object of the present invention can be achieved by using a method ofmanufacturing a terminal-modified polymer, comprising: performing apolymerization reaction of a vinyl aromatic monomer, a conjugated dienemonomer or both in the presence of an anionic polymerization initiatorand then adding an alkoxy aluminum compound thereinto to terminate thepolymerization reaction. Alternatively, a terminal-modified polymer canalso be manufactured by adding an aluminum halide compound instead ofthe alkoxy aluminum compound to terminate the polymerization reaction,and allowing for a reaction with a lower alcohol having 1 to 4 carbonatoms.

Effect of the Invention

In the case of the terminal-modified polymer manufactured by the methodaccording to the present invention, an alkoxy aluminum group can beeasily introduced into a polymer terminal using an alkoxy aluminumcompound or a its equivalent as a terminator for the polymerizationreaction.

When the obtained terminal-modified polymer is compounded as onecomponent in a silica-containing rubber composition for pneumatic tires,the dispersibility of silica compounded into the rubber composition canbe improved. As a result, the objective of simultaneous achievement ofthe reduction of rolling resistance and the stability on a wet road,inherent to silica, can be sufficiently satisfied.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

A polymer to be modified at a terminal group is formed as a polymer of avinyl aromatic monomer, a conjugated diene monomer or both. Vinylaromatic monomers include styrene, α-methylstyrene, p-methylstyrene,2,4,6-trimethylstyrene, vinyltoluene, 1-vinylnaphthalene and the like,and preferably styrene is used. Conjugated diene monomers include, forexample, 1,3-butadiene, isoprene, 1,3-pentadiene,2,3-dimethyl-1,3-butadiene, 1,3-hexadiene, chloroprene and the like, andpreferably 1,3-butadiene or isoprene is used. Further, both of thesevinyl aromatic monomers and conjugated diene monomers can be used incombination at any mixing ratio, and preferably both of styrene and1,3-butadiene or isoprene are used. When both of these are used incombination, the resulting polymer is generally a random copolymer, butit may be a block copolymer.

The polymerization reaction is performed by the anionic polymerizationmethod in which an anionic polymerization initiator is used. As ananionic polymerization initiator, used is an organolithium compound,preferably alkyl lithium or aryl lithium.

Alkyl lithiums include, for example, methyl lithium, ethyl lithium,propyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium,isobutyl lithium, hexyl lithium, octyl lithium, tetramethylenedilithium, m-diisopropenylbenzene dilithium and the like. Aryl lithiumsinclude, for example, phenyl lithium, tolyl lithium and the like. Thesemay be used alone or in combination of two or more, and n-butyl lithium,sec-butyl lithium and tert-butyl lithium are preferred in view ofhandling and industrial economic efficiency, and n-butyl lithium andsec-butyl lithium are more preferred in view of reactivity withmonomers.

In general, these organolithium compounds are used in a rate of about0.0001 to 10 mol %, preferably about 0.0005 to 6 mol % relative to theamount of a charged monomer (mixture).

To the polymerization reaction system, added is2,2-ditetrahydrofurylpropane, N,N,N′,N′-tetramethylethylenediamine,diethyl ether, monoglyme, diglyme, dimethoxyethane, tetrahydrofuran andthe like which are used at a rate of about 10 to 300 mol %, preferablyabout 40 to 200 mol % relative to the molar quantity of an initiatorused. These compounds act as anion initiators and activators for agrowing species or randomizers during copolymerization reaction when anonpolar solvent such as cyclohexane or methylcyclohexane is used forthe polymerization reaction.

The polymerization reaction may be performed, for example, under theconditions of about −100 to 100° C., generally about 0 to 70° C. forabout 1 to 5 hours using a hydrocarbon-based solvent such ascyclohexane, methylcyclohexane, toluene and tetrahydrofuran.Subsequently, an alkoxy aluminum compound is added to the polymerizationreaction system to terminate the polymerization reaction. The alkoxyaluminum compound is used in an amount sufficient for introducing aterminal group of the produced polymer, and is used, for example, at arate of about 33 to 1000 mol %, preferably about 100 to 400 mol %relative to the molar quantity of an anionic polymerization initiatorused.

As the alkoxy aluminum compound, used is a trialkoxy aluminum such astriethoxy aluminum, triisopropoxy aluminum and tri-sec-butoxy aluminum.Preferably, triisopropoxy aluminum is used.

The polymerization reaction may be terminated also by adding an aluminumhalide compound, preferably trichloroaluminum instead of an alkoxyaluminum compound. An alkoxyl group may be formed also by forming agroup derived from an aluminum halide compound at a polymer terminal,and then allowing for a reaction with a lower alcohol such as methanol,ethanol, isopropanol and n-butanol.

The aluminum halide compound is used in an amount sufficient forintroducing a terminal group in the produced polymer as a same in thecase of the alkoxy aluminum compound, and is used, for example, at arate of about 33 to 1000 mol %, preferably about 100 to 400 mol %relative to the molar quantity of an anionic polymerization initiator tobe used. Anionic polymerization used herein is a polymerization methodwhich proceeds along the following processes:

-   -   1) A growing species is generated by a nucleophilic attack of an        initiator on a monomer.    -   2) The growing species further nucleophilically attacks the        monomer and a polymer having a growing terminal is generated by        repeating this process.    -   3) The growing species at a polymer terminal nucleophilically        attacks a terminator to terminate the polymerization.        As a result, each one of terminal to initiate and terminal to        terminate will be introduced into one polymer chain. Therefore,        ideally, a terminator will be used preferably in 1:1, i.e., at a        rate of 100% relative to an initiator, but the lower limit is        set at about 33 mol % herein considering that the terminator        used in the present invention is AlX₃, i.e., trivalent. Further,        the amount of a lower alcohol used for forming an alkoxyl group        is one that is sufficient to completely convert a halogen group        introduced as a terminal group into an alkoxyl group.

The alkoxy aluminum compound forms an Al(OR)₂ group at least at aterminus of the polymer molecule. For example, in a case where styreneand 1,3-butadiene are used as comonomers, or 1,3-butadiene is used aloneas a monomer, a reaction is performed according to the following formulato form a modified polymer having a terminal Al(OR)₂ group along with a—[Al(OR)₂O]n— bond (n: 0 to 50):

The resulting terminal-modified polymer is to be compounded in adiene-based rubber, in particular, a silica containing diene-basedrubber. The terminal-modified polymer is to be used at a rate of 0.1 to30 parts by mass, preferably 1 to 10 parts by mass, relative to thetotal amount of 100 parts by mass including a diene-based rubber. In acase where the ratio of the terminal-modified polymer used is less thanthis, desired modification effects may not be obtained. On the otherhand, in a case where it is used at more than this ratio, processabilityof an unvulcanized rubber may be decreased.

As the diene based rubber, natural rubber (NR), isoprene rubber (IR),butadiene rubber (BR), chloroprene rubber (CR), butyl rubber (IIR),nitrile rubber (NBR), styrene-butadiene rubber (SBR) and the like can beused alone or as a blended rubber, and preferably NR, BR or a blendedrubber thereof can be used. As SBR, any of emulsion-polymerized SBR(E-SBR) and solution-polymerized SBR (S-SBR) can be used. Particularpreferably, the same diene-based rubber as a polymer having anintramolecular double bond, which is used for terminal modification, isused.

Silica or both silica and carbon black may be added to a diene-basedrubber composition in an amount of 10 to 150 parts by mass, preferably30 to 150 parts by mass per 100 parts by mass of a diene-based rubbercontaining a terminal-modified polymer. The addition of these fillers,in particular silica, can reduce rolling resistance and the like.Contrary to this, however, when used at more than this ratio, rollingresistance and the like may be deteriorated.

As the silica, used are those having a BET specific surface area(according with ASTM D1993-03) of 70 to 200 m²/g, preferably 70 to 190m²/g. These are a dry-process silica manufactured by pyrolysis ofsilicon halides or organosilicon compounds and the like and awet-process silica manufactured by acid decomposition of sodium silicateand the like. A wet-process silica is preferably used in view of costand performance. Actually, commercially available products currently onthe market for use in the rubber industry can be used as they are.

In order to enhance characteristics required for silica and thedispersibility in a diene-based rubber (silica has a poor affinity withrubber polymers, and also has a characteristic in which silica mutuallyforms a hydrogen bond in a rubber through a silanol group, resulting ina decreased dispersibility of silica into the rubber), a silane couplingagent is to be compounded in an amount of 1 to 20 parts by mass,preferably about 3 to 18 parts by mass per 100 parts by mass of adiene-based rubber containing a thioester-modified polymer. As thesilane coupling agent, the following are preferably used:bis(trialkoxysilylpropyl)sulfide which has an alkoxysilyl group thatreacts with a silanol group on the surface of silica and a sulfur chainthat reacts with a polymer,

(RO)₃Si(CH₂)₃—(S)_(n)—(CH₂)₃Si(OR)₃

-   -   R: an alkyl group having 1 to 2 carbon atoms    -   n: an integer of 1 to 4        for example, bis(3-triethoxysilylpropyl)tetrasulfide,        bis(2-triethoxysilylethyl)tetrasulfide,        bis(3-trimethoxysilylpropyl)tetrasulfide,        bis(3-triethoxysilylpropyl) disulfide and the like.

As the carbon black, commonly used is furnace black such as SAF, ISAF,HAF, FEF, GPF and SRF. Such a carbon black, which is an effectivecomponent for forming a tread part, in particular a cap tread part, of apneumatic tire, is used along with silica in a rate of 3 to 120 parts bymass per 100 parts by mass of a diene-based rubber containing aterminal-modified polymer.

In a rubber composition comprising each component described above as anessential component, sulfur as a vulcanizing agent and any one or moreof vulcanization accelerators such as thiazole-based agents (MBT, MBTS,ZnMBT and the like), sulfenamide-based agents (CBS, DCBS, BBS and thelike), guanidine-based agents (DPG, DOTG, OTBG and the like),thiuram-based agents (TMTD, TMTM, TBzTD, TETD, TBTD and the like),dithiocarbamate-based agents (ZTC, NaBDC and the like) andxanthate-based agents (ZnBX and the like), preferably asulfur-containing vulcanization accelerator are to be compoundedFurther, other compounding agents commonly used as compounding agentsfor rubber may be appropriately compounded, if desired, including, forexample, a reinforcing agent or a filler such talc, clay, graphite andcalcium silicate, a processing aid such as stearic acid; zinc oxide, asoftener, a plasticizers, an antioxidant and the like.

A composition can be prepared by kneading with a kneading machine or amixer such as a kneader and a Banbury mixer, and an open roll and thelike by a general method. After molded into a predetermined shape, theresulting composition is vulcanized at a vulcanizing temperaturedepending on the types of diene-based rubber, vulcanizing agent,vulcanization accelerator used and a compounding ratio thereof to form atread part of a pneumatic tire and the like.

EXAMPLES

Next, the present invention will be described with reference toExamples.

Example 1

To a 100 ml two-necked flask,

-   -   cyclohexane (Kanto Chemical Co., Inc.) 7 ml    -   2,2-ditetrahydrofurylpropane 0.248 g (1.35 mmol)        -   (Tokyo Chemical Industry Co., Ltd.)    -   n-hexane solution of n-BuLi 2 ml (3.30 mmol)        -   (Kanto Chemical Co., Inc.; concentration: 1.65 mol/L)            were charged under the conditions of room temperature, and            to the resulting solution,    -   styrene (the same manufacturer as above) 5.90 g (56.6 mmol)        was added dropwise at 0° C., and stirred for 3 hours.        Subsequently, a suspension of 1.35 g (6.61 mmol) of        triisopropoxy aluminum (the same manufacturer as above) in 10 ml        tetrahydrofuran was added to terminate the polymerization        reaction.

The obtained reaction mixture was filtered using a filter paper,volatile components were distilled off from the filtrate, and theresidue was dissolved in 30 ml of tetrahydrofuran. Then the solution wasadded dropwise to 200 ml of methanol to separate a methanol solublecomponent and a methanol insoluble component. The same procedure wasrepeated twice, and volatile components were distilled off to obtain5.78 g (yield: 98%) of a white solid terminal-modified polystyrene.

-   -   Mn: 2960    -   Mn (the number average molecular weight) was measured by SEC        (size exclusion type chromatography), and a value of Mn was        estimated as a polystyrene reduced molecular weight    -   PDI: 1.1    -   PDI (polydispersity index) was calculated as Mw/Mn using values        of Mw (the weight average molecular weight) and Mn, which were        measured by SEC        A value of PDI being closer to 1 indicates that a polymer having        a more controlled molecular weight distribution was obtained    -   R_(f): 0.86    -   A value of R_(f) was measured by TLC (thin layer chromatography)        with a silica plate, and a smaller value indicates a higher        affinity with silica    -   ¹H-NMR (CDCl₃, 20° C.): δ=7.3 to 6.9 (br)        -   6.9 to 6.7 (br)        -   6.7 to 6.2 (br)        -   5.0 to 4.8 (br)        -   3.8 to 3.6 (br)        -   2.4 to 2.2 (br)        -   2.1 to 1.2 (br)        -   1.2 to 0.9 (br)        -   0.8 to 0.7 (br)

Example 2

2.24 g (yield: 85%) of a white viscous liquid terminal-modifiedpolybutadiene was obtained as in Example 1 except that the amounts of2,2-ditetrahydrofurylpropane and triisopropoxy aluminum were changed to0.316 g (1.72 mmol) and 1.61 g (7.88 mmol), respectively, and 17.6 g(48.8 mmol) of 15 wt % n-hexane solution of 1,3-butadiene (Aldrich) wasused instead of styrene.

-   -   Mn: 1880    -   PDI: 1.1    -   R_(f): 0.82    -   ¹H-NMR (CDCl₃, 20° C.): δ=5.9 to 5.7 (br)        -   5.6 to 5.2 (br)        -   5.1 to 4.8 (br)        -   3.9 to 3.7 (br)        -   2.3 to 1.7 (br)        -   1.6 to 1.0 (br)        -   0.8 to 0.7 (br)

Example 3

3.90 g (yield: 91%) of a white viscous liquid terminal-modifiedstyrene-butadiene copolymer was obtained as in Example 1 except that theamounts of 2,2-ditetrahydrofurylpropane and triisopropoxy aluminum werechanged to 0.331 g (1.80 mmol) and 1.60 g (7.83 mmol), respectively, anda mixture of 11.4 g (31.6 mmol) of 15 wt % n-hexane solution of1,3-butadiene and 2.58 g (24.8 mmol) of styrene was used instead ofstyrene alone.

-   -   Mn: 2920    -   PDI: 1.1    -   R_(f): 0.83    -   ¹H-NMR (CDCl₃, 20° C.): δ=7.4 to 6.9 (br)        -   6.9 to 6.2 (br)        -   5.8 to 5.0 (br)        -   5.0 to 4.4 (br)        -   3.8 to 3.6 (br)        -   2.6 to 0.9 (br)        -   0.9 to 0.7 (br)

Example 4

5.43 g (yield: 92%) of a white viscous liquid terminal-modifiedpolystyrene was obtained as in Example 1 except that the amount of2,2-ditetrahydrofurylpropane was changed to 0.309 g (1.68 mmol), and1.07 g (8.02 mmol) of trichloroaluminum was used instead oftriisopropoxy. In the case of this Example, the methanolysis reaction isbelieved to occur due to the methanol used in the purification step(this is the same in Examples 5 to 6).

-   -   Mn: 3880    -   PDI: 1.2    -   R_(f): 0.78    -   ¹H-NMR (CDCl₃, 20° C.): δ=7.2 to 6.9 (br)        -   6.9 to 6.7 (br)        -   6.7 to 6.1 (br)        -   3.8 to 3.6 (br)        -   2.4 to 2.2 (br)        -   2.1 to 1.2 (br)        -   1.2 to 0.9 (br)        -   0.9 to 0.7 (br)

Example 5

2.17 g (yield: 83%) of a white viscous liquid terminal-modifiedpolybutadiene was obtained as in Example 1 except that the amount of2,2-ditetrahydrofurylpropane was changed to 0.336 g (1.82 mmol), and17.4 g (48.3 mmol) of 15 wt % n-hexane solution of 1,3-butadiene wasused instead of styrene, and further 1.13 g (8.48 mmol) oftrichloroaluminum was used instead of triisopropoxy aluminum.

-   -   Mn: 2240    -   PDI: 1.1    -   R_(f): 0.80    -   ¹H-NMR (CDCl₃, 20° C.): δ=6.0 to 5.6 (br)        -   5.6 to 5.1 (br)        -   5.1 to 4.8 (br)        -   3.9 to 3.7 (br)        -   2.3 to 1.6 (br)        -   1.6 to 1.0 (br)        -   0.9 to 0.6 (br)

Example 6

5.86 g (yield: 87%) of a white viscous liquid terminal-modifiedstyrene-butadiene copolymer was obtained as in Example 1 except that theamounts of 2,2-ditetrahydrofurylpropane and trichloroaluminum, which wasused instead of triisopropoxy aluminum, were changed to 0.355 g (1.92mmol) and 1.61 g (12.1 mmol), respectively, and a mixture of 15.5 g(43.0 mmol) of 15 wt % n-hexane solution of 1,3-butadiene and 4.41 g(42.3 mmol) of styrene was used instead of styrene alone.

-   -   Mn: 4220    -   PDI: 1.2    -   R_(f): 0.80    -   ¹H-NMR (CDCl₃, 20° C.): δ=7.5 to 6.9 (br)        -   6.9 to 6.1 (br)        -   5.9 to 5.0 (br)        -   5.0 to 4.3 (br)        -   3.8 to 3.6 (br)        -   2.6 to 0.9 (br)        -   0.9 to 0.6 (br)

Example 7

-   -   4.37 kg of cyclohexane, 300 g of styrene and 734 g of butadiene        were weighed out, thrown into an autoclave for polymerization        and stirred at 50° C. To the resulting mixture solution, 0.858 g        of tetramethylethylenediamine and further 4 mL of n-butyl        lithium (1.60 mol/L) were added and stirred at 50° C. for 3        hours. Then, a THF (20 mL) suspension of 2.09 g of triethoxy        aluminum was added and stirred at 50° C. for 3 hours to        terminate the polymerization. After volatile components were        distilled away from the polymer solution, reprecipitation        treatment was performed in which a polymer component is thrown        into methanol (6.5 kg) to separate the polymer component.        Volatile components were further distilled away from the polymer        component under reduced pressure. As a result, 962 g (yield:        93%) of a terminal-modified polymer was obtained.    -   Mn: 299,000    -   PDI: 1.2    -   R_(f): 0.80    -   ¹H-NMR (CDCl₃, 20° C.): δ=7.5 to 6.9 (br)        -   6.9 to 6.1 (br)        -   5.9 to 5.0 (br)        -   5.0 to 4.3 (br)        -   3.8 to 3.6 (br)        -   2.6 to 0.9 (br)        -   0.9 to 0.6 (br)

Example 8

Terminal-modified styrene-butadiene 80.00 parts by mass copolymerobtained in Example 7 BR (Zeon Corporation, BR1220) 20.00 parts by massSilica (Rhodia operations, Zeosil Premium 80.00 parts by mass 200MP)Carbon black (Tokai Carbon Co., Ltd., 5.00 parts by mass Seast KHP)Stearic acid (NOF Corporation, YR) 2.00 parts by mass Fatty acid ester(Schill & Seilacher, 1.00 parts by mass HT207) Antioxidant (SolutiaEurope, 6ppd) 1.50 parts by mass Coupling agent (Evonik Degussa, Si69)6.40 parts by mass Process oil (Showa Shell Sekiyu K.K., 30.00 parts bymass Extra No. 4S) Zinc oxide 3.00 parts by mass (Seido ChemicalIndustry Co., Ltd., Zinc oxide No. 3) Vulcanization accelerator A 2.00parts by mass (Sumitomo Chemical Industry Co., Ltd., Soxinol D-G)Vulcanization accelerator B 1.70 parts by mass (Ouchi Shinko ChemicalIndustrial Co., Ltd., Nocceler CZ-G) Sulfur (Karuizawa Refinery,oil-treated 1.50 parts by mass sulfur)Among the above components, those except for the vulcanizationaccelerator and sulfur were kneaded for 5 minutes in a 1.7 L closedBanbury mixer, and the kneaded material was dumped out of the mixer tocool to room temperature. Subsequently, the vulcanization acceleratorand sulfur were mixed with the same Banbury mixer. The resultingunvulcanized rubber composition was press-vulcanized for 30 minutes at150° C. to obtain a vulcanized rubber.

Mooney viscosity was measured for an unvulcanized rubber composition,and each of RPA (the vulcanization Payne's effect), tensile strength,impact resilience (40° C.), fully automatic elongation and hightemperature elongation was measured for the vulcanizate. The measuredvalues obtained were expressed as an index where a value for anunmodified styrene-butadiene copolymer (Mn: 293,000) is taken as 100.

-   -   Mooney viscosity (viscosity ML₁₊₄ [M]): 108        -   according with JIS K6300        -   Usually, a smaller index corresponds to lower viscosity and            means superior processability        -   However, in this case, a larger value means superiority            since a reciprocal value is used herein    -   RPA (the vulcanization Payne's effect): 104        -   according with ISO 11345        -   A smaller index indicates a larger Payne's effect, meaning a            superior dispersibility of silica    -   Tensile strength: 96        -   according with JIS K6251    -   Impact resilience (40° C.): 99        -   according with JIS K6255    -   Fully automatic elongation: 102    -   High temperature elongation: 118        -   according with JIS K6251/6301:2006 corresponding to ISO 48            for both        -   A larger index means better elongation of rubber            The above results reveal that a diene-based rubber            composition having good processability, a large Payne's            effect and excellent elongation properties was able to be            obtained.

1. Method of manufacturing a terminal-modified polymer, comprising:allowing for a polymerization reaction of a vinyl aromatic monomer, aconjugated diene monomer or both in the presence of an anionicpolymerization initiator; and then adding an alkoxy aluminum compoundthereinto to terminate the polymerization reaction.
 2. Method ofmanufacturing a terminal-modified polymer according to claim 1, whereintrialkoxy aluminum is used as the alkoxy aluminum compound.
 3. Method ofmanufacturing a terminal-modified polymer, comprising: allowing for apolymerization reaction of a vinyl aromatic monomer, a conjugated dienemonomer or both in the presence of an anionic polymerization initiator;and adding an aluminum halide compound thereinto to terminate thepolymerization reaction; and then allowing for a reaction with a loweralcohol having 1 to 4 carbon atoms.
 4. Method of manufacturing aterminal-modified polymer according to claim 3, whereintrichloroaluminum is used as the aluminum halide compound.
 5. Method ofmanufacturing a terminal-modified polymer according to claim 1, whereina polymer having a group derived from the alkoxy aluminum compound at aterminal site is formed.
 6. Method of manufacturing a terminal-modifiedpolymer according to claim 1, wherein styrene or a derivative thereof isused as the vinyl aromatic monomer.
 7. Method of manufacturing aterminal-modified polymer according to claim 1, wherein 1,3-butadiene orisoprene is used as the conjugated diene monomer.
 8. Method ofmanufacturing a terminal-modified polymer according to claim 1, whereinan organolithium compound is used as the anionic polymerizationinitiator.
 9. Diene-based rubber composition in which aterminal-modified polymer manufactured by method according to claim 1,is compounded in a diene-based rubber.
 10. Method of manufacturing aterminal-modified polymer according to claim 3, wherein a polymer havinga group derived from the alkoxy aluminum compound at a terminal site isformed.
 11. Method of manufacturing a terminal-modified polymeraccording to claim 3, wherein styrene or a derivative thereof is used asthe vinyl aromatic monomer.
 12. Method of manufacturing aterminal-modified polymer according to claim 3, wherein 1,3-butadiene orisoprene is used as the conjugated diene monomer.
 13. Method ofmanufacturing a terminal-modified polymer according to claim 3, whereinan organolithium compound is used as the anionic polymerizationinitiator.
 14. Diene-based rubber composition in which aterminal-modified polymer manufactured by method according to claim 3,is compounded in a diene-based rubber.